Hold Up Time
Hold up time represents the duration a PSU can maintain stable output as defined by the ATX specification without input power. This is very important when the quality of your electricity varies and there are short drops in the supply (dips or brownouts).
In the oscilloscope screenshots below, the blue line is the AC input mains signal, the green line the "Power Good" signal, and the yellow line the +12V rail. The measured timing variable is listed as ΔX.
Hold Up Time
AC Loss To PWR_OK Hold Up Time
PWR_OK Inactive to DC Loss Delay
Hold up time exceeds 17 ms, which is long enough. That having been said, the similarly priced competition does better here.
Timings for Alternative Sleep Mode (ASM)
Traditionally, sleep mode (S3) shuts the system off for minutes or even hours to reduce power consumption. However, this approach adds a few seconds of delay when resuming from standby.
Microsoft recently introduced Modern Sleep, which brings the instant-on capability to PCs, just like your phone instantly turns on without any noticeable delay. Modern Sleep builds on the Alternative Sleep Mode capability Intel has defined. To support Alternative Sleep Mode and ensure system stability, a power supply must wake up from sleep quickly—think of it as the PSU's boot time.
Source: IntelTimings for Alternative Sleep Mode |
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Parameter | Description | Recommended Value |
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T0 | AC power on time | < 2s |
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T1 | Power-on time | < 150 ms |
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T2 | Rise time | 0.2 - 20 ms |
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T3 | PWR_OK delay | 100 - 150 ms |
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T4 | PWR_OK rise time | < 10 ms |
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T5 | AC loss to PWR_OK hold-up time | > 16 ms |
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T6 | PWR_OK inactive to DC loss delay | > 1 ms |
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For the reviewed PSU, we measured T1 and T3 at 20% and 100% load.
T1 (Power-on time) & T3 (PWR_OK delay) |
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Load | T1 | T3 |
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20% | 73 ms | 142 ms |
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100% | 74 ms | 150.5 ms |
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The PWR_OK signal is within 100–150 ms in the first test, which suggests this PSU is compatible with alternative sleep mode (ASM). However, it is slightly above 150 ms in the second test, so there is no way to be sure as there are no compatible mainboards to try it out. That having been said, I don't think anyone will manage to fully load this PSU while utilizing ASM.